Cell Envelope Homeostasis in Bacillus subtilis

项目总结 细菌被一个对生长、完整性和致病至关重要的细胞膜所包围。这个 包膜和构建它的生物发生途径也是我们许多最有效的抗生素的靶标 和疫苗疗法。由于细胞包膜生物发生一直是一个如此成功的目标，它一直是一个 半个多世纪以来的活跃研究领域。大多数负责合成和重塑的基因 对不同的表面聚合物进行了鉴定，并对其生化活性进行了表征。然而， 我们对这些不同的组装途径是如何相互调节和协调的理解 在此期间，增长仍然有限。 这项建议集中在与细菌如何协调包膜组装有关的两个悬而未决的问题上， 两者都主要集中在细胞壁肽聚糖(PG)上。细胞生长需要PG的合成，但也需要 细胞壁水解酶的活性，以允许PG网络的扩张。这些潜在的裂解酶是如何 在所有细菌中，调节和协调生长仍然是一个悬而未决的问题。的前两个目标 本研究重点研究了模式革兰氏阳性菌枯草芽孢杆菌如何在功能上调节两种细菌 冗余细胞壁水解酶及其活性与细胞壁合成和包膜的协调 扩张。第三个目标集中在细胞如何感知和响应细胞壁生物发生的扰动。这个 二十多年前，σM信号通路被认为是一种应激反应通路，它是由 环境压力，包括针对抗生素的细胞壁。这条途径在中间水平是活跃的。 在细胞包膜不受干扰的生长和功能稳态过程中，监控包膜组装和 通过PG生物发生途径调节通量。这条通路感知到什么以及它是如何传递这一信息的 膜上的信息一直是个谜。拟议研究的结果将澄清 包膜生物发生中的关键调控途径，并将为开发新的治疗方法提供信息 感染。本申请的具体目标是： 目的1：阐明细胞如何感知和响应PG的交联度，以确保适当的扩增 细胞壁。 目的2研究生长过程中细胞壁水解与细胞壁合成的协调关系。 目的3：确定细胞如何感知和响应细胞包膜生物发生的扰动。

PROJECT SUMMARY Bacteria are surrounded by a cell envelope that is essential for growth, integrity, and pathogenesis. The envelope and the biogenesis pathways that build it are also the target of many of our most effective antibiotic and vaccine therapies. Because cell envelope biogenesis has been such a successful target, it has been an active area of research for over half a century. Most of the genes responsible for the synthesis and remodeling of the different surface polymers have been identified and their biochemical activities characterized. However, our understanding of how these different assembly pathways are regulated and coordinated with each other during growth remains limited. This proposal focuses on two outstanding questions related to how bacteria coordinate envelope assembly, both principally focused on the cell wall peptidoglycan (PG). Cell growth requires PG synthesis but also the activity of cell wall hydrolases to allow expansion of the PG meshwork. How these potentially lytic enzymes are regulated and coordinated with growth remains an unanswered question in all bacteria. The first two aims of this proposal focus on how the model gram-positive bacterium Bacillus subtilis regulates two functionally redundant cell wall hydrolases and how it coordinates their activities with cell wall synthesis and envelope expansion. The third aim focuses on how cells sense and respond to perturbations to cell wall biogenesis. The σM-signaling pathway was identified over two decades ago as a stress-response pathway that is induced upon environmental stresses, including cell wall targeting antibiotics. This pathway is active at intermediate levels during unperturbed growth and functions in cell envelope homeostasis, monitoring envelope assembly and adjusting flux through the PG biogenesis pathway. What this pathway senses and how it transduces this information across the membrane have remained mysterious. The results of the proposed studies will elucidate critical regulatory pathways in envelope biogenesis and will inform the development of new treatments for infections. The Specific Aims of this application are: Aim 1: Elucidate how cells sense and respond to the extent of PG crosslinking to ensure proper expansion of the cell wall. Aim 2 Investigate how cell wall hydrolysis is coordinated with cell wall synthesis during growth. Aim 3: Determine how cells sense and respond to perturbations to cell envelope biogenesis.